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Shareholder Report, Line Graph (Details) 190991_Buffalo High Yield Fund_Investor Class_TSR Annual {Investor Class} - USD ($)
12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Mar. 31, 2023
Mar. 31, 2022
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Mar. 31, 2016
Mar. 31, 2026
Investor Class                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Buffalo High Yield Fund Investor Class
Accumulated Value $ 16,552 $ 15,427 $ 13,765 $ 13,994 $ 13,724 $ 10,800 $ 11,571 $ 11,184 $ 10,837 $ 10,000 $ 17,304
Bloomberg U.S. Universal Bond Index [Member]                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     Bloomberg U.S. Universal Bond Index
Accumulated Value 11,777 11,190 10,899 11,426 11,931 11,589 10,815 10,346 10,192 10,000 $ 12,324
ICE BofA U.S. High Yield Index [Member]                      
Account Value [Line Items]                      
Line Graph and Table Measure Name                     ICE BofA U.S. High Yield Index
Accumulated Value $ 16,867 $ 15,665 $ 14,097 $ 14,608 $ 14,651 $ 11,882 $ 12,839 $ 12,119 $ 11,688 $ 10,000 $ 18,044